Background: Symptomatic cerebral thromboembolism occurs in 0.4% of transcatheter atrial fibrillation ablation procedures. Silent cerebral events, instead, have recently been reported in up to 14%, especially clustered within patients undergoing cardioversion at the end of the procedure. The present study reports the incidence of silent cerebral thromboembolism, assessed by cerebral MRI, delaying electrical cardioversion, in case of lack of sinus rhythm restoration at the end of the procedure, after 4 weeks of effective anticoagulation.
Methods and results: Ninety-five consecutive patients with antiarrhythmic drug refractory atrial fibrillation were referred for transcatheter ablation and enrolled in the study. All patients underwent pre-ablation and post-ablation cerebral MRI. Overall, post-ablation cerebral MRI registered new thromboembolism in six (6%) patients. Fifty-five (58%) patients remained in sinus rhythm throughout the procedure and 40 (42%) reported persistent atrial fibrillation, yielding a silent thromboembolism incidence of 5 and 8%, respectively. In particular, silent thromboembolism was registered in one (4%) of the 25 patients achieving sinus rhythm by catheters, in two (18%) of the 11 patients spontaneously restoring sinus rhythm shortly following the procedure and in none of the four patients cardioverted following 4-week anticoagulation. In a matched reference population, a significantly higher percentage of patients (15, 16% vs. 6, 6%; P = 0.03) suffered from a new post-ablation thromboembolism; particularly within patients terminating the procedure in atrial fibrillation. Delaying cardioversion reduced silent cerebral thromboembolism from 38 to 13%.
Conclusion: Delaying electrical cardioversion after a 4-week anticoagulation period reduced the risk of silent cerebral thromboembolism and is a viable and safer option in patients terminating a transcatheter ablation procedure in atrial fibrillation.